My car has an intermittent problem. Sometimes it will run perfect and other times it will just be sitting idling and almost stall or actually stall. Almost like im turning the key off and on real fast. it also runs a lot more sluggish, less power and pretty lean when its having the problem. I brought it to my mechanic who only works on muscle cars and performance cars and he couldn't figure it out. Says it happens randomly and to fast to diagnose so he wants me to bring it back when it gets worse? was having a mis problem but changed all the plugs wires and opti and ran perfect. I don't know if it is a coincidence or not but a day or two after i put my new magnaflow catback on it started doing it. Changed fuel filter. Im gonna check fuel pressure also. Im stumped maybe the kid before me had it tuned specifically to the SLP exhaust? Or maybe some wires are loose under the dash? Any suggestions?

 

Is this problem at startup or while the car is running it just randomly starts doing this? Or is it when it hits closed loop it starts doing it? Maybe an O2 sensor?

Try to get a DataMaster file and let someone on here who knows how to read them real well see if they can tell whats going on.

 

Check for a bad maf connection. Wiggle the connector slowly while the car is running.